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Topic Title: Active power filters & power factor correction
Topic Summary: Help and advice required for specification understanding...urgent
Created On: 11 August 2012 10:40 PM
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 11 August 2012 10:40 PM
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parky1969

Posts: 1
Joined: 11 August 2012

Hi Guys
i wonder if i could draft a few moments of some of you guys.
The company i work for have tendered for a reasonable size project comprising 3 separate buildings on the same lot. All electrical systems are supplied through one inlet.
We have 3 main distribution panels with some 50 other MSB's.
8 lifts, 130 VRV air conditioning systems, 800 high frequency ballast type lights and various other equipment.
Drawings are good, however there is nothing to note the APF and PFC equipment. The spec states predict and provide harmonic filters to all main distribution panels for automatic sensing and correction.

We had in our tender provided 3 - the designer is now stating we require some 36 APF and PFC units - all 4 wire type at a considerable cost.

Is there anyway that we could of predicted the APF and PFC required for all this equipment without calculating all the required data from the manufacturers?

Would it be sufficient to supply the 3 main distribution panels with APF &PFC without the need for every MSB having these installed.

If any of you have regulations to quote or are fully conversant with APF & PFC's standards and could offer some help i would very much like to hear from you ASAP.

**** i understand that mostly all equipment has to be supplied with harmonic filtration now as part of the EC machines directive, am i correct and would this solve my issue???****

Best Regards

Andrew

acp01@tesco.net
 12 August 2012 06:07 PM
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davezawadi

Posts: 2712
Joined: 26 June 2002

I assume that you are in the EC and all the kit you are using is CE marked. This means that it complies with the directives for mains harmonics, so you should need to do nothing there. The PFC is a bit more complex. You will have to check the manufacturers data on all the major items, they will (possibly needing a telephone prod) provide power factor data. It is a boring job and should have been done by the designer when he specified your additional 36 items. Ask him for information, as it is unusual to correct the power factor in small bits, usually only at the intake. It would help to know which country this is.

-------------------------
David
CEng etc, don't ask, its a result not a question!
 12 August 2012 08:37 PM
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Jaymack

Posts: 4676
Joined: 07 April 2004

Originally posted by: parky1969
Is there anyway that we could of predicted the APF and PFC required for all this equipment without calculating all the required data from the manufacturers?

If there is no information on the PF of equipment, estimate the total running kW or kVA loading and assume a P.F. of 0.85. The PFC should then be designed for the kVAr requirement. It is most economical to install PFC at the source of supply, this could also be of the automatic type to improve the PF to around 0.95.

There is a standard calculation to determine the most economical P.F. for the installation, dependent on capital cost, depreciation, future and present values and M.D. tariff etc. etc., but equipment suppliers should assist in this.

Regards
 12 August 2012 09:56 PM
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John Peckham

Posts: 7515
Joined: 23 April 2005

It might be worth Power Logging the supply for a week to see what the PF and loads look like. You could also have a look at the harmonics.

-------------------------
John Peckham

http://www.astutetechnicalservices.co.uk/
 13 August 2012 05:56 AM
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Jaymack

Posts: 4676
Joined: 07 April 2004

Originally posted by: John Peckham
It might be worth Power Logging the supply for a week to see what the PF and loads look like. You could also have a look at the harmonics.

At the estimating stage? Akin to attempting a post mortem without a corpse!

Regards
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